The present invention relates to a cushioned surface structure, such as for a tennis court.
Current tennis court surfaces generally fall under three categories: grass or lawn type surfaces; compacted clay surfaces; and hard surfaces. These surfaces are different in appearance and playing characteristics. For example, grass courts are characterized by a very fast surface that enhances the speed of a tennis game. However, these court surfaces are expensive to install and maintain and may cause erratic ball behavior. Grass courts also suffer from the disadvantage that they are seasonal.
Clay courts are characterized by a soft, spin receptive surface which induces slow play and helps reduce player injuries. However, clay courts require high maintenance and are also limited to seasonal use because of weather conditions.
Hard court surfaces generally include an asphalt or concrete base painted over with, for example, an acrylic latex water based emulsion. Hard court surfaces are the most common surfaces for tennis courts because they require very little maintenance and are not limited to seasonal use such as with grass and clay surfaces. However, hard court surfaces are the least forgiving of all court surfaces and may cause joint, ligament and/or tendon damage to players. Hard court surfaces are also disadvantageous in that they cause excessive wear to shoes and tennis balls, typically cause a tennis ball to bounce too high, and are not spin receptive enough to reward a good tennis shot.
Attempts have been made to produce a court surface that combines the soft and forgiving nature of clay or grass courts with the advantages of hard courts, such as wearability and low maintenance. For example, elastomeric compositions applied over concrete or asphalt surfaces are commonly used in the new construction of tennis courts to increase the resiliency of the playing surface. In one such approach, for example, a base layer of liquid polyurethane containing resilient material, such as pulverized rubber, is applied over a prepared surface of concrete, asphalt, timber, compacted earth or the like. A conventional tennis court coating, such as a color-fill coating, is typically applied over the base layer to provide a smooth, flat surface.
Most state-of-the-art surfaces that utilize elastomeric compositions suffer a number of disadvantages. For example, polyurethane/rubber surfaces, such as described above, are extremely expensive due to the high polyurethane content. In addition, the base layer of elastomeric particles is extremely porous, and therefore absorbs a significant amount of coating material as it is applied over the base layer. Consequently, an unusually large amount of coating material is required to fill the voids of the base layer and provide a smooth exposed surface. It is readily appreciated that the high cost of conventional coating materials can be prohibitive.
Thus, a need exists for a new and improved cushioned surface structure, such as for a tennis court, and methods for making the same.
The present invention concerns a cushioned surface that has particular applicability to sport surfaces such as tennis courts, although the surface may be used in other applications as well. Other applications may include, for example, basketball courts, weight rooms, racquetball courts, tracks, garage floors, driveways and other surfaces.
Generally speaking, the surface includes one or more elastomeric layers comprising elastomeric particles, such as ground tire rubber, applied to a base surface such as concrete or asphalt. The elastomeric layers may comprise either loose elastomeric particles, or a matrix of elastomeric particles and an adhesive binder. Each elastomeric layer may be adhesively secured to an adjacent layer with a suitable adhesive, such as an acrylic binder.
To fill the voids of the elastomeric layers and provide a smooth, flat playing surface, one or more fill layers may be formed over the elastomeric layers. The fill layers desirably consist of a dry fill material, such as silica sand. A tennis court coating-compound, such as a color-fill system, may be applied over the top fill layer. Finally, one or more layers of a color mix may be applied over the color-fill system.
Using one or more fill layers to fill the voids in the elastomeric layers prior to the application of the coating-compound is advantageous because the fill layer(s) prevent the coating-compound from being absorbed into the elastomeric layers. Consequently, this reduces the amount of coating-compound that is required, which in turn reduces the overall installation cost of the court.
More specifically, a cushioned surface structure according to one representative embodiment comprises at least one elastomeric layer comprising at least 5% by weight of elastomeric particles, and more desirably, at least 50% by weight of elastomeric particles. At least one fill layer consisting of dry fill material, such as dry silica sand, overlays the first layer and fills the voids between the elastomeric particles. Although not required, white silica sand is preferred because its ability to reflect light facilitates the identification of surface imperfections in the fill layer. An adhesive layer comprising, for example, an acrylic binder, may be applied on top of each layer of the surface structure to bond together adjacent layers.
The surface structure also may include a conventional tennis court coating-compound layer, such as a color-fill layer, overlaying the fill layer, and a color-coating layer overlaying the coating-compound layer.
In particular embodiments, the surface structure comprises at least a lower elastomeric layer comprised entirely of loose elastomeric particles and at least an upper elastomeric layer comprising a matrix of elastomeric particles and a binder. Desirably, the elastomeric particles of the lower elastomeric layer are generally larger in size than the elastomeric particles of the upper elastomeric layer. Also, the lower and upper elastomeric layers desirably are formed such that the density of elastomeric particles in the lower layer is greater than the density of elastomeric particles in the upper elastomeric layer.
In addition, where more than one fill layer is used, the particle size of the fill material desirably is greatest in the lowermost fill layer, and the particle size decreases in one or more succeeding upper layers. In one disclosed embodiment, for example, two fill layers of #30 silica sand are applied over the elastomeric layers and two fill layers of #70 silica sand are applied over the fill layers of #30 silica sand.
According to another representative embodiment, a cushioned surface structure comprises at least one elastomeric layer comprising elastomeric particles. A first fill layer consisting of dry fill material overlays the elastomeric layer and a second fill layer consisting of dry fill material overlays the first fill layer. Desirably, the particle size of the fill material of the first fill layer is generally larger than the particle size of the fill material of the second fill layer.
A cushioned surface structure according to yet another representative embodiment comprises a first elastomeric layer of elastomeric particles and a second elastomeric layer of elastomeric particles overlaying the first elastomeric layer. Desirably, the elastomeric particles of the first elastomeric layer are generally larger in size than the elastomeric particles of the second elastomeric layer. In addition, at least one of the first and second elastomeric layers desirably comprises a matrix of elastomeric particles mixed in an adhesive binder. At least one fill layer of dry fill material for filling the voids in the elastomeric layers may be applied over the elastomeric layers.
According to another representative embodiment, a method of forming a cushioned surface structure includes forming at least one elastomeric layer comprising at least 5% by weight of elastomeric particles. At least one fill layer, consisting of dry fill material, such as dry silica sand, is applied over the elastomeric layer to fill in the voids between the elastomeric particles.
Another method of forming a cushioned surface structure includes applying at least a lower elastomeric layer of elastomeric particles over a sub-surface, and applying at least an upper elastomeric layer of elastomeric particles over the lower elastomeric layer. At least one fill layer is applied over the upper elastomeric layer for filling the voids of the elastomeric layers.
These and other features of the invention will be more fully appreciated when the following detailed description of the invention is read in conjunction with the accompanying drawings.